Higher performance rotary wing aircraft are sought. A stopped-rotor (or rotor/wing) aircraft like that shown in U.S. Pat. No. 3,327,969 offers the ability to hover like a helicopter plus the promise of achieving the high speeds of a fixed-wing aircraft by stopping the rotor's rotation while in flight and allowing it to act as a fixed wing.
Another prior art example of a stopped-rotor aircraft, the Canard Rotor/Wing (CRW) concept (U.S. Pat. No. 5,454,530), combines a reaction-driven, stoppable-rotor with a high-lift canard and tail. Exhaust gas from a common power plant (i.e. gas turbine engine) provides direct thrust required for fixed-wing flight and is routed to the blade tips to power the reaction-driven rotor for rotary-wing flight. Together the canard and tail provide all of the aircraft's lift during transition between rotary-wing and fixed-wing flight, thereby allowing the rotor to be unloaded during starting and stopping.
It is known that all reaction driven rotors have their own unique inefficiencies. Coriolis losses associated with accelerating the propulsive gases radially as the rotor blade spins consumes up to 40% of power available. Thus, stopped-rotor aircraft designs are sought that are more efficient than the reaction-driven, rotor/wing system of the CRW.